patch 8.1.2281: 'showbreak' cannot be set for one window

Problem:    'showbreak' cannot be set for one window.
Solution:   Make 'showbreak' global-local.
diff --git a/src/testdir/test_breakindent.vim b/src/testdir/test_breakindent.vim
index 90c0ca5..ee61cbc 100644
--- a/src/testdir/test_breakindent.vim
+++ b/src/testdir/test_breakindent.vim
@@ -62,7 +62,8 @@
 
 func Test_breakindent02()
   " simple breakindent test with showbreak set
-  call s:test_windows('setl briopt=min:0 sbr=>>')
+  set sbr=>>
+  call s:test_windows('setl briopt=min:0 sbr=')
   let lines = s:screen_lines(line('.'),8)
   let expect = [
 	\ "    abcd",
@@ -122,7 +123,8 @@
 
 func Test_breakindent04()
   " breakindent set with min width 18
-  call s:test_windows('setl sbr= briopt=min:18')
+  set sbr=<<<
+  call s:test_windows('setl sbr=NONE briopt=min:18')
   let lines = s:screen_lines(line('.'),8)
   let expect = [
 	\ "    abcd",
@@ -132,6 +134,7 @@
   call s:compare_lines(expect, lines)
   " clean up
   call s:close_windows('set sbr=')
+  set sbr=
 endfunc
 
 func Test_breakindent04_vartabs()
diff --git a/src/testdir/test_highlight.vim b/src/testdir/test_highlight.vim
index 9e1af97..83bada5 100644
--- a/src/testdir/test_highlight.vim
+++ b/src/testdir/test_highlight.vim
@@ -425,6 +425,7 @@
   let [hiCursorLine, hi_ul, hi_bg] = HiCursorLine()
 
   call NewWindow('topleft 5', 10)
+  set showbreak=xxx
   setlocal breakindent breakindentopt=min:0,shift:1 showbreak=>
   call setline(1, ' ' . repeat('a', 9) . 'bcd')
   call matchadd('Search', '\n')
@@ -482,6 +483,7 @@
 
   call CloseWindow()
   set showbreak=
+  setlocal showbreak=
   exe hiCursorLine
 endfunc